The present invention relates to telecommunication, and especially to a method mobile station and inter-working unit for dynamic radio capacity controlling. The mobile station comprises a radio unit for transceiving data over an air interface, a data interface unit for transceiving data to and from the radio unit, and a control unit for controlling the operation of the radio unit and the interface unit. The method comprises the steps of transceiving information over a first interface and transceiving information over a second interface, the first interface being the air interface. The inter-working unit comprises a data interface unit connected to a radio network unit communicating with at least one mobile station over an air interface, and a control unit for controlling the operation of the data interface unit unit.
Many existing digital wireless or mobile telephone networks make use of time division multiple access (TDMA) to share out radio resources between a number of mobile stations and between a number of channels. For example, in the European Telecommunications Standards Institute (ETSI) GSM standard, a given frequency band is divided in the time domain into a succession of frames, known as TDMA (Time Division Multiplexed Access) frames. The length of a TDMA frame is 4.615 ms. Each TDMA frame is in turn divided into eight consecutive slots of equal duration. In the conventional circuit switched transmission mode, when a call is initiated, a full rate bi-directional traffic channel (TCH/F) is defined for that call by reserving two time slots (1 to 8), in each of a succession of TDMA frames, for the duration of the call. One of these slots provides the downlink from the base station (BS) to the mobile station (MS) whilst the other provides the uplink.
The circuit switched transmission mode in GSM provides for a data transmission rate of 9.6 kbps. However, due to the demand for higher transmission rates, a set of GSM enhancements known as GSM Phase 2+ have been specified by ETSI. One of the main features of GSM Phase 2+ is known as High Speed Circuit Switched Data (HSCSDxe2x80x94specified in GSM 02.34 and GSM 03.34) which achieves an increased data transmission rate by using more than one TCH/F for a single connection (i.e. effectively reserving two or more consecutive time slots in each TDMA frame).
GSM Phase 2+ also specifies (see for example GSM 01.60, 02.60, 03.60, and 03.64) a new feature known as General Packet Radio Service (GPRS). GPRS provides for the dynamic allocation of radio resources, with the allocation for uplink and downlink communications being made separately and independently of each other. That is to say that a time slot is allocated to a particular MS to BSS link only when there is data to be transmitted. The unnecessary reservation of a TCH/F, when there is no data to be transmitted, is thus avoided. In addition, a high-speed packet switched transmission channel may be provided by assigning two or more slots of a TDMA frame to a single MS.
In GSM HSCSD non-transparent connection mode the user can (if the MS supports this feature) request service level up- or downgrading, i.e. request more or less time slots to be allocated for a connection. Provided that the feature is requested in the set-up of a call, service level up- and downgrading is possible during an ongoing call. For example, when setting up a connection to an Internet Service Provider (ISP), the login and authorisation procedures do not require a lot of transmission capacity and could therefore be managed with one time slot connection. When the connection is established and a large file or a www-page (World Wide Web) containing graphics is being downloaded, more transmission capacity is needed. When the file or the www-page are downloaded and the user is reading the information, the need for capacity is not that big anymore, and a small number of time slots are needed.
In GPRS, a Temporary Block Flow (TBF) is generally initiated for delivering packet data units between the MS and the network. For each temporary flow, the need for resources is negotiated, and immediately after the flow, the resource is released for the use of traffic to and from other MSs. GPRS comprises two allocation modes, a fixed allocation and a dynamic allocation. In the fixed allocation a detailed fixed uplink resource is allocated for the MS, and an option for renegotiation of the radio resource during TBF is also defined.
The advantage of using a correct amount of capacity, i.e. correct number of time slots at each time draws from the fact that the user pays for the connection depending on the amount of time slots used. The less capacity is used, i.e. the less time slots are wasted, and the less the user has to pay. In addition, this approach is advantageous also with respect to the network, since the same resources can be used to facilitate services for a remarkably larger number of users.
However, according to the present system definitions,to facilitate such a feature of up- or downgrading in service level, the application running in the MS must be adapted to support this feature. This means that for example, a www-browser or an email application in the MS must be adapted to recognise that the connection used is a GSM connection employing multiple time slots, and that service level up- and downgrading is supported by the mobile. So far no such applications exist, and even if some such applications were created, mobile subscribers would always be limited to those few adapted applications available.
According to the first aspect of the invention the mobile station is characterized by its control unit being adapted to monitor a property of a data flow through the interface unit for deriving a reference value for the monitored property of the data flow; said control unit being provided with at least one threshold value for the monitored property; and said control unit being adapted to compare the derived reference value with the threshold value, and being adapted, as a response to a certain relation of said reference number and said threshold value, to initiate a request for radio resource modification.
In the solution according to the invention, the user data to be transmitted over the air interface is monitored, and based on the properties of this data e.g. the number of time slots allocated for the connection is controlled. Consequently, the data processing entity connected to the MS and running the applications does not have to be involved with the control of the radio resource used for the connection, and modifications to the applications in order to support this enhanced use of radio resource become unnecessary. The present invention enables the user to easily benefit from the dynamic nature of the data link and reduces the need for special application software which would have to be tailored for mobile communication environment in order to facilitate utilisation of available dynamic multi-slot features.
In the later embodiments of the invention the mobile station monitors the amount of the transmitted data, or the contents of the data frames transmitted in the physical layer level. According to the invention, certain criteria will be set for the properties of the data, and whenever said criteria are met, a request for service level modification is initiated by the mobile station.
According to a second aspect of the invention an inter-working unit of a mobile system supporting high speed circuit switched data transmission is introduced. The inter-working unit comprises a data interface unit (IU) connected to a radio network unit (BSC, BTS) communicating with at least one mobile station over an air interface, and a control unit (CPU) for controlling the operation of the data interface unit unit. The inter-working unit is characterized by said control unit being adapted to monitor a property of a data flow through the interface unit for deriving a reference value for the monitored property of the data flow; said control unit being provided with at least one threshold value for the monitored property; said control unit being adapted to compare the derived reference value with the threshold value, and being adapted, as a response a certain relation of said reference number and said threshold value, to initiate a request for radio resource modification.
According to a third aspect of the invention, a method for controlling data transfer over the air interface is presented. The method comprises transceiving information over a first interface and transceiving information over a second interface, the first interface being the air interface. The method is characterized by monitoring a property of the data flow through the first interface for deriving a reference value for the monitored property of the data flow; providing at least one threshold value for the monitored property; comparing the derived reference value to the threshold value; and initiating, as a response to a certain relation of said reference number and said threshold value, a request for radio resource modification.